The overall goal of this project is to determine whether arthroscopic meniscectomy in degenerative meniscal tears is beneficial from a clinical and scientific viewpoint relative to a non-meniscectomy arthroscopy control. Arthroscopic meniscectomy is among the most commonly performed orthopedic surgical procedures in the VA system and nationally. In the investigators' practice at the VA Palo Alto Healthcare System over the last year, 80% of patients having knee arthroscopy for meniscus tears have been in the 45-70 years age group and 53% of these patients had degenerative meniscal tears without a large unstable flap. these data are comparable to arthroscopic meniscectomy data drawn in other settings. While meniscectomy is a common procedure there remains substantial uncertainty regarding the short term benefits and the long term consequences of arthroscopic meniscectomy in patients with degenerative meniscus tears. Of major concern is the fact that degenerative meniscus tears are associated with osteoarthritis, and it is known that within two years of surgery, arthroscopic debridement for osteoarthritis is no better than placebo in relieving pain and restoring function. Longer term, meniscectomy has been shown to be associated with elevated risk of osteoarthritis development, raising the concern that meniscectomy can actually be harmful. It has also been shown by the group that patients with clinically successful arthroscopic posterior medial meniscectomy have significant change in the rotational motion of the knee during walking. Rotational changes at the knee follow soft tissue damage and have been implicated in the causes for cartilage degeneration.